1. Technical Field
The present invention relates to a both-direction display method and a both-direction display apparatus.
2. Related Art
A both-direction display apparatus configured to display images on the basis of an image signal input from an external device and images of objects such as characters, drawing, and the like corresponding to an operation for a screen in a composite form is known. Here, an image on the basis of the image signal input from the external device is referred to as an external image, and an object corresponding to the operation for the screen is referred to as an operation input object.
JP-A-2013-152739 discloses a both-direction projector configured to operate in a drawing mode in which an operation input object is drawn on the basis of an operation for a screen and a mode transmitting an operation signal such as a click to an external device on the basis of the operation for the screen (referred to as an external device operating mode).
In the case of presentations or lessons in a school by using a projector, a user may want to write characters or graphics on a projected image for explanation. In this case, there is a method of inputting characters or graphics by operating a pointing device such as a mouse on a screen of a personal computer connected to the projector and configured to input image data.
In JP-2011-140154 discloses an electronic blackboard system configured to allow input of characters or graphics by operating an electronic pen (a pen-type input device) on an image projected on a screen.
JP-A-8-160539 discloses a light blackboard configured to provide an image projecting device configured to project an image from a back surface side of the screen with a predetermined image display at a position of an input of an instruction operation given to a front surface side of the screen. JP-A-8-160539 describes that a drawing control is performed from a pen-type element, and the screen of drawings is erased.
Since the image signal input from the external device to the both-direction projector is a signal for displaying an image drawn by the external device, if the operation for the screen is performed in the external device operation mode, the external image is changed. In contrast, the operation input object is an image drawn by the both-direct ion projector, and is not involved at all by the external device when being processed.
Therefore, in the both-direction projector described in JP-A-2013-152739, even though the external image is changed by the operation for screen performed in the external device operating mode, the operation input object is not changed. Therefore, for example, in the case where an external image indicating a specific slide of an application program and an operation input object indicating a comment corresponding to the specific slide are displayed in a composite form for presentation, when the mode is transferred from the drawing mode to the external device operating mode and a next slide is selected by the operation for the screen, the next page is displayed with a comment which is not related to the next slide. In order to erase the operation input object which is not related to the slide, an operation for erasing the operation input object is disadvantageously required in addition to the operation for selecting the next slide.
When inputting drawings such as characters and graphics (drawing data) on the projected image (image data) with the electronic pen, there is a case that returning to the image before inputting the drawing is wanted for conformation. However, with the apparatus as the electronic blackboard system disclosed in JP-2011-140154, drawing data needs to be specified one by one or selected for erasing these drawings in order to erase these drawings. In addition, in the case of restoring the drawing data after having erased and continuing drawing, a complicated operation such as saving the drawing data in a certain location and calling up the drawing data again is required. The light blackboard of the JP-A-8-160539 is only capable of erasing the drawn images in a lump by the pen-type element and is not capable of restoring the drawing images again after having erased.